Mechanical belting



April 28, 1970 BAXENDALE ET AL 3,509,006

MECHANICAL BELTING Filed Oct. 12, 1964 In /a mfars Newman G. Baxendq per WK lfiobmsorl United States Patent 3,509,006 MECHANICAL BELTING Norman Gilby Baxendale, Liverpool, and Peter Michael Robinson, Woolton, Liverpool, England, assignors to The Dunlop Company Limited, London, England, a British company Filed Oct. 12, 1964, Ser. No. 403,129 Claims priority, application Great Britain, Oct. 22, 1963, 41,601/ 63 Int. Cl. F16g 1/10; B65g /34 US. Cl. 161-91 15 Claims ABSTRACT OF THE DISCLOSURE Mechanical belting having a twill-woven reinforcement including woven first and second Warp yarns, the first warp yarns being of greater breaking strength than the second warp yarns which second warp yarns under normal loads serve to resist straightening of the first warp yarns by tying down the weft yarns.

This invention relates to mechanical belting having one or more plies of a woven textile fabric as a reinforcement.

According to the present invention mechanical belting comprises a textile reinforcement embedded in a flexible elastomeric material, the textile reinforcement comprising a twill-woven textile fabric having load-bearing warp yarns not being substantially surface bonded to the flexible elastomeric material, and other warp yarns being surface bonded to the flexible elastomeric material and serving to resist reduction of the crimp of the load-bearing warp yarns at loads at least up to the working load of the belt, said other warp yarns having a breaking strength not greater than of the breaking strength of said loadbearing warp yarns, the ratio of the number of said other warp yarns to the number of load-bearing warp yarns in the weave repeat being from 1:1 to 1:2, and no more than two load-bearing warp yarns being adjacent, and the weft of said twill woven textile fabric being substantially surface bonded to the elastomeric material.

By the term surface bonded as used in this specificcation there is meant actual adhesion between the surface of the yarn and the flexible elastomeric material. By the term not substantially bonded as used in this specification it is meant that there is no actual adhesion between the surface of the yarn and the elastomeric material, but it is to be understood that the yarns are nevertheless securely mechanically locked within the elastomeric material.

The mechanical belting according to the present invention comprises one or more plies of the twill woven fabric embedded within the flexible elastomeric material forming the working surface of the belting which can be any natural or synthetic rubber composition or flexible elastomeric resinous material such as plasticized polyvinyl chloride.

The textile reinforcement comprises a fabirc woven with a twill weave or a re-arranged (broken) twill weave and has load-bearing warp yarns which serve to carry the working load when the belt is in use. These loadhearing yarns are not substantially surface bonded to the elastomeric material but are securely mechanically locked within the belt to resist the reduction in crimp of the yarns when the belt is in use. The yarns are of the type that do not have a fibrous surface or a chemically treated surface which would promote surface adhesion with the fiexible elastomeric material. The type of yarns chosen will depend on the use to which the belt is to be put and on the nature of the covering material since some yarns 3,509,006 Patented Apr. 28, 1970 in an untreated state may bond at their surface to one particular elastomeric material and not to another, e.g.

untreated non-fibrous rayon will bond to plasticized polyvinyl chloride compositions but not to rubber. Examples of suitable yarns, depending on the elastomeric material, are yarns formed from polyesters such as poly(ethylene glycol terephthalate), polyamides, regenerated cellulose fibres such as rayon, polyvinyl alcohol and polypropylene. If desired, one or more types of load-bearing yarns can be employed in the textile reinforcement.

The textile reinforcement contains other warp yarns which have a breaking strength not greater than $5 of the breaking strength of the load-bearing warp yarns. The other warp yarns serve to resist a reduction of the crimp of the load-bearing warp yarns at loads at least up to the working load of the belting, and to do this the ratio of the number of other warp yarns to the number of load-bearing yarns in the weave repeat should be from 1:1 to 1:2 and no more than two load-bearing yarns should be adjacent. The other warp yarns should be of the type that bond at their surface to the elastomeric material and for this purpose can be fibrous yarns or nonfibrous yarns which have been chemically treated to promote adhesion with the elastomeric material. Examples of yarns that can be used as the other warp yarns are cotton or fibrous rayon or chemically treated polyamide yarns. It is possible to use the yarn formed from a mixture of a fibrous yarn and an untreated non-fibrous yarn such as that produced by doubling cotton with a polyamide yarn.

The weft of the textile reinforcement should be substantially surface bonded to the elastomeric material and for this purpose fibrous yarns or chemically treated yarns can be employed such as cotton or fibrous rayon or chemically treated polyamide yarns. It is possible to use the yarn formed from a mixture of a fibrous yarn and an untreated non-fibrous yarn such as that produced by doubling cotton with a polyamide yarn.

The woven textile fabric contains load-bearing warp yarns not substantially surface bonded to the cover material and other warp yarns which are substantially surface bonded to the cover material. At loads up to the working load of the belt the other warp yarns serve to resist reduction of the crimp applied to the load-bearing warp yarns, but at loads above the Working load the crimp of the load-bearing Warp yarns is reduced and this confers desirable extensibility properties on the belting. In order to achieve these advantageous properties it is preferable that the load-bearing warp yarns and the other warp yarns have substantially the same crimp, which crimp may be, for example, between 7 percent and 14 percent.

However, the other warp yarns may, if desired, have a greater crimp than the load-bearing warp yarns, but in this case the difference in crimp between the load-bearing warp yarns and the other warp yarns should not exceed about 10 percent. By the term crimp as used in this context there is meant the percentage difference in length between the actual length of the yarn and the length of the fabric containing the yarn.

The load bearing warp yarns should be a material having a high melting point so that the yarns are not melted or otherwise damaged at the temperatures used for vulcanising the cover material to consolidate the belting. For this reason the fabric should not contain a low melting poly(ethylene glycol) terephthalate yarn or a low melting polyamide yarn.

The mechanical belting constructed in accordance with the present invention possesses a lower elongation at the working load than belting in which the reinforcement is a plain woven fabric or a twill woven fabric which does not contain the mixture of load-bearing yarns and other warp yarns. The load-bearing yarns of the present mechanical belting are securely mechanically locked in position within the belt, and it is believed that this is partly the result of' the elastomeric material penetrating the woven fabric and filling the interstices of the weave to maintain the weft yarns in a fixed relation to the loadbearing yarns, and partly the result of adhesion of the weft and other warp yarns to the elastomeric material, thereby preventing straightening or reduction in crimp of the load bearing yarns.

Mechanical belting is usually designed to work at a load of up to 15 percent of its ultimate breaking load. The breaking load depends on the strength of the loadbearing yarns and on the number of plies of the textile reinforcement in the belt. Belting constructed in accordance with the present invention is advantageous in that it has a low elongation at the working load but has a high elongation at break. The load-bearing yarns are more securely locked in position within the belt than if the textile reinforcement was a plain woven fabric. The belts can be made to trough in use, if required.

The invention will now be illustrated by way of example only with reference to the accompanying drawings, in which:

FIGURE 1 shows a plan view of a mechanical belt constructed in accordance with the present invention, various parts of the belt being cut away to show the construction in detail,

FIGURE 2 shows an enlarged plan view of the fabric used in the belt shown in FIGURE 1, and

FIGURE 3 shows an enlarged plan view of an alternative form of fabric to that shown in FIGURE 2.

Referring to FIGURE 1, a mechanical belt 1 consists of three layers 2, 3 and 4 of woven textile fabric embedded in a plasticized polyvinyl chloride composition 5. The fabric layers 2, 3 and 4 are each of substantially the same width, which width is slightly less than the width of the mechanical belt 1 so that the edges of the belt 1 are formed of the plasticized polyvinyl chloride composition 5.

Each of the fabric layers 2. 3 and 4 consists of woven fabric 6 as shown in FIGURE 2. The fabric 6 is a twillwoven fabric having load-bearing warp yarns 7, and other warp yarns 8 which are not load-bearing warp yarns. The load-bearing Warp yarns 7 alternate with the other warp yarns 8 across the width of the fabric 6. The warp yarns 7 and 8 are interwoven with weft yarns 9. The loadbearing warp yarns 7 are made of a material, e.g. polyethylene glycol terephthalate, the surface of which does not bond substantially to the plasticized polyvinyl chloride composition 5 in which the fabric 6 is embedded. The other warp yarns 8 are of a material, e.g. cotton, the surface of which bonds readily to the plasticized polyvinyl chloride composition 5. The weft yarns 9 are made of a material which is readily bonded to the plasticized polyvinyl chloride composition, and may be made for instance of cotton, or of cotton and nylon doubled together.

In the mechanical belt 1 shown in FIGURE 1, the surface of the load-bearing warp yarns 7 is not substantially bonded to the plasticized polyvinyl chloride composition 5, but the yarns 7 are securely mechanically locked in position by the other warp yarns 8 and the weft threads 9 which are securely surface-bonded to the placsticized polyvinyl chloride composition 5.

In FIGURE 3 there is shown a twill-Woven fabric 10 which may be used instead of the fabric 6 in making the mechanical belt 1 shown in FIGURE 1. This fabric again is made of load-bearing warp yarns 7 and other warp yarns 8 interwoven with the weft threads 9, but in the fabric 10 two load-bearing warp yarns 7 are arranged between each warp yarn 8 and the next warp yarn 8. In the fabric 6 shown in FIGURE 2, each of the warp yarns 8 has a different path through the weft threads 9 than either of the load-bearing warp yarns 7 adjacent to it, whereas in the fabric 10 shown in FIGURE 3, each of the warp yarns 8 has the same path through the weft threads 9 as one of the load-bearing warp yarns 7 adjacent to it.

The invention is further illustrated by the following examples:

EXAMPLE I A mechanical belt as described above and shown in FIGURES 1 and 2 of the accompanying drawings was produced having load-bearing warp yarns 7 each made of 12 fold 1000 denier polyethylene terephthalate yarns available under the trade name Terylene, other warp yarns 8 each made of 7 fold 7s count cotton yarns, and weft yarns 9 each formed by twisting together 4 yarns each of which consists of 1 end of 7s count cotton doubled with 1 end of untreated 840 denier polyamide yarn available under the trade name nylon. The fabric has 14 Terylene warp yarns and 14 cotton warp yarns per inch, and 9 weft yarns per inch, and three layers of the fabric are embedded in a plasticized polyvinyl chloride composition.

1 The belt was tested under working conditions and was found to have a breaking load of about 2,000 pounds per inch per ply of fabric, and a percentage elongation of 1.4 at a Working load of 200 pounds per inch per ply.

For purposes of comparison, a mechanical belt was produced having 5 plies of a Terylene duck fabric embedded in a plasticized polyvinyl. chloride composition. Each ply of the Terylene duck fabric weighed 28 ounces per yard X 42 inches. The belt had a breaking load of 5,800 pounds per inch, i.e. about 1,160 pounds per inch er ply, and an elongation of 2 to 2 /2 percent at a working load of 580 pounds per inch. The belt had an elongation at break of 14 to 16 percent.

Also for purposes of comparison, a mechanical belt was produced having 5 plies of a cotton duck fabric embedded in a plasticized polyvinyl chloride composition. Each ply of the cotton fabric weighed 32 ounces per yard x 42 inches. The belt had a breaking load of 1,180 pounds per inch, i.e. about 236 pounds per inch per ply and an elongation of 3 to 3 /2 percent at a working load of 118 pounds. The belt had an elongation at break of 12 to 15 percent.

EXAMPLE II A mechanical belt was produced constructed of four plies of the fabric as shown in FIGURE 3 of the accompanying drawings embedded in a plasticized polyvinyl chloride composition. Each ply of fabric had load bearing warp yarns 7 made of 30 fold 1000 denier Terylene yarns, other warp yarns 8 made of 7 fold 7s count cotton, and weft yarns 9 formed by twisting together 4 yarns each of which comprises 1 end of 840 denier nylon and 1 end of 7s count cotton doubled together. The fabric had 12 Tery'lene warp yarns and 6 cotton warp yarns per inch, and 10 weft yarns per inch.

The belt had a breaking load of 4,000 pound per inch per ply, an elongation at break of 25 percent, and an elongation of 1.5 percent under a working load of 400 pounds per inch per ply.

Having now described our claim is:

1. Mechanical belting comprising a flexible elastomeric material having embedded therein a textile reinforcement, the textile reinforcement comprising a twill-woven assembly of warp and weft yarns, the woven warp yarns of the assembly including load-bearing first warp yarns having crimp and being substantially free of surface bonding to the flexible elastomeric material, and second warp yarns having crimp and being surface bonded to the fiexi ble elastomeric material, the second warp yarns having a breaking strength not greater than one-tenth of the breaking strength of the first warp yarns and serving to tie down the weft yarns so as to resist straightening of the first warp yarns at loads at least up to the working load of the belt, the ratio of the number of second warp invention, what we yarns to the number of first warp yarns in the weave repeat being from 1:1 to 1:2 so that no more than two first warp yarns are adjacent, and the weft of the twillwoven textile fabric being surface bonded to the elastomeric material.

2. Mechanical belting according to claim 1 in which the reinforcement comprises a textile fabric woven with a rearranged twill weave.

3. Mechanical belting according to claim 1 in which the load-bearing first warp yarns are made of polyethylene glycol terephthalate.

4. Mechanical belting according to claim 1 in which the load-bearing warp yarns are made of a polyamide.

5. Mechanical belting according to claim 1 in which said second warp yarns are made of a fibrous textile ma terial which bonds to the flexible elastomeric material.

6. Mechanical belting according to claim 1 in which said second warp yarns are made of a non-fibrous textile material which has been chemically treated to promote adhesion to the elastomeric material.

7. Mechanical belting according to claim 5 in which said second warp yarns are made of fibrous regenerated cellulose yarns.

8. Mechanical belting according to claim 6 in which said second wrap yarns are made of chemically-treated non-fibrous rayon yarns.

9. Mechanical belting according to claim 6 in which said second wrap yarns are made of chemically-treated polyamide yarns.

10. Mechanical belting according to claim 1 in which said second wrap yarns comprise fibrous yarns and nonfibrous yarns.

11. Mechanical belting according to claim 10 in which said second wrap yarns are made of cotton and a polyamide.

12. Mechanical belting according to claim 1 in which the weft yarns are formed by twisting together cotton and polyamide yarns.

13. Mechanical belting according to claim 1 in which the flexible elastomeric material is a natural rubber composition.

14. Mechanical belting according to clalm 1 in which the flexible elastomeric material is a synthetic rubber composition.

15. Mechanical belting according to claim 1 in which the flexible elastomeric material is a plasticized polyvinyl chloride composition.

References Cited UNITED STATES PATENTS 3,205,119 9/1965 Paul 16191 2,570,576 10/1951 Lord 161-90 X ROBERT F. BURNETT, Primary Examiner M. A. LITMAN, Assistant Examiner US. Cl. X.R. 74232; 198-193 

